mfd: pm8xxx-pwm: add pre-divide=6 and update macros

Add pre-divide=6 and update the max period based on new pre-divide.
Also update pre-divide related macros for better readability.

Change-Id: I5298c373c78f8723dab9a735e4d94f89798800d5
Signed-off-by: Willie Ruan <wruan@codeaurora.org>
2 files changed